Cubic Feet Per Minute (CFM)

Definition - What does Cubic Feet Per Minute (CFM) mean?

Cubic feet per minute (CFM) is a volumetric unit of measurement while expressing gas, air or liquid flow. CFM is mainly used in measurement of ventilation engineering and industrial hygiene. It states the volumetric rate of flow of any gas or air in or out of a space. The higher the CFM coefficient, the more the amount of air or gas is being pushed through that space. 1 CFM is approximately 0.47 liter per second.

Safeopedia explains Cubic Feet Per Minute (CFM)

To calculate air flow in CFM, the following equation may be used.

Q = V x A

Here,

Q = air flow in CFM

V = flow velocity in feet per minute

A = duct cross sectional area

CFM is rather a confusing term. It has no standardization. Basically, CFM means cubic feet per minute, but gasses get compressed at the exit if it is smaller than entrance. Again, if the gas temperature is more at the exit, then more volume of air or gas will leave the space, but not necessarily the mass. Exhaust fan also will pump a constant volume of air though not mass at any other air density.